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In this paper, the manufacturing challenges and related technological solutions concerning the prototyping of microwave ablation (MWA) probes are addressed. In particular, the intertwined aspects pertaining probe design, fabrication and target performance are tackled. The development of a 14G MWA probe prototype, working at a frequency of 2.45 GHz, is proposed as a case study, describing design efforts and the use of rapid prototyping technologies combined with other manufacturing processes. A specific focus is dedicated to the insulating part of the probe radiating section, featuring high aspect ratio and complex shape, which was fabricated by means of Digital Light Processing (DLP) and by using a biocompatible material, the EnvisionTEC E-Shell® 300. Furthermore, the probe handling, properly designed to arrange cables and tubes routing, was fabricated by means of Fused Deposition Modeling (FDM) technology. Finally, ex vivo experiments conducted on bovine liver showed satisfactory treatment performance and structural reliability of the 14G MWA probe prototype. Besides being characterized by a good impedance matching ( S11 = −25 dB), prototype performance were also in good agreement with design simulations and even satisfying if compared to other results available in literature as, with an input radiation power of 40 W, the ablated zone after a 10 min treatment exhibited a ratio of the radial and longitudinal axis of 0.66.

At the present time, there is a growing interest in additive manufacturing (AM) technologies and their integration into current process chains. In particular, the implementation of AM for tool production in micro injection molding (µ-IM), a well-established process, could introduce many advantages. First of all, AM could avoid the need for the time-consuming and expensive fabrication of molds for small series of customized products. In this work, the feasibility, quality, and reliability of an AM/µ-IM process chain were evaluated by designing and fabricating mold inserts for µ-IM by stereolithography (SLA) technology, the mold inserts were characterized and tested experimentally. The selected geometry is composed of four thin cavities: This particular feature represents an actual challenge for both the SLA and µ-IM perspective due to the large surface-to-volume ratio of the cavity. Two different materials were used for the mold fabrication, showing sharply different performance in terms of endurance limit and cavity degradation. The obtained results confirm that the µ-IM process, exploiting an SLA fabricated mold insert, is feasible but requires great accuracy in material choice, mold design, fabrication, and assembly.

Micro-applications, especially in biomedical and optical sectors, require the fabrication of thin polymeric parts which can be commonly realized by micro-injection molding process. However, this process is characterized by a relevant constraint regarding the tooling. Indeed, the design and manufacturing of molds could be a very time-consuming step and so, a significant limitation for the rapid development of new products. Moreover, if the design displays challenging microfeatures, their realization could involve the use of more than one mold for the fabrication of a single thin part. Therefore, proper integration of different manufacturing microtechnologies may represent an advantageous method to realize such polymeric thin microfeatures. In this work, a micromanufacturing process chain including stereolithography, micromilling, and micro-injection molding is reported. The mold for the micro-injection molding process was fabricated by means of stereolithography and micromilling, which allowed us to produce low-cost reconfigurable modular mold, composed of insert support and a removable insert. The assessment of the proposed process chain was carried out by evaluating the dimensions and the surface finishing and texturing of the milled mold cavities and molded components. Finally, a brief economic analysis compares three process chains for fabricating the micromold showing that the proposed one reduces the manufacturing cost by almost 61% with the same production time.

This paper discusses the performance of micro-electro-discharge machining (micro-EDM) process using different flushing media. Several tests have been performed considering a hardened steel thin workpiece machined via micro-EDM drilling and through-trench and different flushing fluids: deionized water, tap water, deionized water with Garnet, tap water with Garnet. Garnet is the abrasive material exploited in the micro-AWJ and the concentration per liter of water considered in micro-EDM experiments is the same as required in micro-abrasive water jet (micro-AWJ) machining. A customized system has been built on micro-EDM Sarix SX 200 HP machine to allow the water-based fluid refill and liquid level monitoring during the experiments. The micro-EDM trials have been carried out considering two machining regimes, roughing and semi finishing. The different water-based fluids have different electrical conductivities, which lead to different machining performance. Material removal rate (MRR) and tool wear ratio (TWR) have been estimated in terms of average and standard deviation. The results show that the presence of Garnet does not affect MRR consistently, since the particles do not play an active role in the erosion process but affect surface quality, as proved by the inspection of crater morphology and dimensions estimation performed via confocal microscope. For the considered experiments, MRR is generally increased as the conductivity decreases, in particular when semi-finishing regime is used. Also TWR decreases dramatically with the use of water-based fluids, since a protective recast layer is also deposited on the tool tip preventing wearing. Our analysis shows that micro-EDM can be successfully performed using the same liquid (water and abrasive) used in micro-AWJ, and so paves the way towards the implementation of a hybrid process based on micro-AWJ and micro-EDM technologies.

Measuring 3D micro-features is a challenging task that is usually performed using high-cost systems generally based on technologies with narrow working ranges and very accurate control of the sensor positions. Well-known image analysis methods, such as Photogrammetry, would likely lower the costs of 3D inspection of micro-features and add texture information to the 3D models; however, the behaviour of Photogrammetry is strongly affected by the scaling method because it retrieves a model that must be scaled after its computation. In this paper, an experimental study of the validity of a hybrid 3D image processing method for measuring micro-features is presented. This method exploits the Depth-from-Focus method to retrieve the correct scale for a photogrammetric model. The measurement of properly-designed and manufactured specimens was performed by following and adapting the German guideline VDI/VDE 2634, Part 3 to validate the method using calibrated specimens. The proposed system has been demonstrated to be very promising can achieve an error of less than 10 μm.

In fused deposition modeling (FDM) process, several uncertainty sources contribute to low accuracy and bad surface finishing. Besides intrinsic uncertainties, other factors, related to the machine structure and actuation, participate to increase complexity and reduce the controllability of the process. On-board vision systems can be successfully exploited to monitor the deposition process and to acquire quantitative information on geometry and transients. This information can be used to calibrate the process parameters where a compensation strategy is implemented. In this paper, a low-cost vision system capable of microscopic acquisitions is integrated into an FDM machine and image-processing techniques are exploited to define calibration procedures to improve the process accuracy, thus extending the use of this equipment to micromanufacturing applications. The effectiveness of the integration is evaluated through the fabrication of a microfluidic device.

The capability to manufacture high-precision components with microscale features is enhanced by the combination of different micromanufacturing processes in a single process chain. This study explores an effective process chain that combines micro-abrasive water jet (μ-AWJ) and microwire electrical discharge machining (μ-WEDM) technologies. An experimental spring component is chosen as a leading test case, since fine geometric features machining and low roughness on the cut walls are required. The advantages deriving from the two technologies combination are discussed in terms of machining time, surface roughness, and feature accuracy. First, the performances of both processes are assessed by experimentation and discussed. Successively, different process chains are conceived for fabricating two test cases with different sizes, displaying some useful indications that can be drawn from this experience.

Additive Manufacturing (AM) technologies have recently emerged as key technologies to be integrated in current process chains. In particular, AM technologies could be successfully applied for molds and inserts fabrication for small batches production of components and microcomponents. In terms of economy and sustainability, the AM offers several advantages with respect to traditional manufacturing technologies for molds and inserts fabrication, such as waste reduction, minimized energy consumption, reduced cycle time and time to market. In this work, a thin cavities mold insert was manufactured via inverted (bottom-up) stereolitography (SLA) and tested via micro-injection molding in order to assess the feasibility of the SLA/?-IM (Injection Molding) process chain. The designed geometry is composed by four thin cavities: this particular feature represents the actual challenge, due to the large surface to volume ratio that characterizes the sample. Design rules for AM have been applied in order to fulfill injection molding issues and ensure a longer mold insert duration. The mold insert cavities have been characterized to evaluate the achieved dimensional and geometrical precision showing a quite good geometry accuracy in thickness; the mold insert geometrical deviation, which could prevent the correct assembly of the insert into the mold, have been measured too. Finally, a short-series of about 30 molding cycles has been carried out evaluating the capacity of filling the thin cavities and the capability of SLA mold insert.

The surface to volume ratio in micro injection molding is quite large and this makes interfacial phenomena particularly crucial for the effectiveness of the process. This criticality is more evident for thin parts molding, where the influence of roughness on the thermal boundary conditions is not negligible. In this case, the contact between polymer and mold significantly affects the heat transfer at the interface and consequently it strongly influences the polymer melt flow behavior. In this paper, the effects of the polymer-mold interface on polymer flow were experimentally investigated. In particular, the filling of a representative micro part with a thickness of 100 μm was studied in relation to surface roughness and mold wettability. The results showed that the state of the polymer-mold interface plays a fundamental role in the filling of thin-wall micro injection molding. In particular, the flow length increases with both the mold roughness and the contact angle between the molten polymers and the cavity surface.

The fabrication of personalised prostheses tailored on each patient is one of the major needs and key issues for the future of several surgical specialties. Moreover, the production of patient-specific anatomo-functional models for preoperative planning is an important requirement in the presence of tailored prostheses, as also the surgical treatment must be optimised for each patient. The presence of a prototyping service inside the hospital would be a benefit for the clinical activity, as its location would allow a closer interaction with clinicians, leading to significant time and cost reductions. However, at present, these services are extremely rare worldwide. Based on these considerations, we investigate enhanced methods and technologies for implementing such a service. Moreover, we analyse the sustainability of the service and, thanks to the development of two prototypes, we show the feasibility of the production inside the hospital.

Lab-on-chips (LoCs) are microsystems capable of manipulating small amounts of fluids in microfluidic channels. They have a huge application potential, from basic science to chemical synthesis and point-of-care medical analysis. Polymers are rapidly emerging as the substrate of choice for LoC production, thanks to a low material cost and ease of processing. Two breakthroughs that could promote LoC diffusion are a microfabrication technology with cost-effective and rapid prototyping capabilities and also an integrated on-chip optical detection system. This chapter proposes the use of femtosecond laser micromachining combined with microinjection moulding as a novel highly-flexible microfabrication platform for polymeric LoCs with integrated optical detection, for the realization of low-cost and truly portable biophotonic microsystems. We demonstrate a LoC for the relevant application of non-invasive and contactless mechanical phenotyping of single cancer cells.

Micro Injection molding combined with the use of removable inserts is one of the most promising manufacturing process for microfluidic devices, such as Lab-on-a-chip, that have the potential to revolutionize the healthcare and diagnosis system. In this work we have designed, fabricated and tested a compact and disposable plastic optical stretcher. To produce the mould inserts, two micro manufacturing technologies have been used. Micro Electro Discharge machining was used to reproduce the inverse of the capillary tube connection characterized by high aspect ratio. Thanks to the high accuracy of femtosecond laser machining, instead, we manufactured insert with perfectly aligned microfluidic channels and fiber slots, facilitating the final composition of the optical manipulation device. The optical stretcher operation is tested using microbeads and red blood cells solutions. The prototype presented in this work demonstrates the feasibility of this approach that should guarantee a real mass production of ready-to-use- Lab-on-a-chip.

The present study explores the design of an effective process chain that combines micro Abrasive Waterjet (micro-AWJ) and micro Wire Electro Discharge Machining (micro-WEDM) technologies. An experimental spring component is chosen as leading test case, since fine geometric features machining and low roughness on the cut walls are required. The advantages deriving from the two technologies combination are discussed in terms of machining time, surface roughness and feature accuracy. First, the performance of both processes are assessed by experimentation and discussed. Successively, different process chains are conceived for realizing two test cases with different size, displaying the advantages and drawbacks of the combinations.

The aim of the present study is the assessment of the integration of a low cost optical measurement device into a high-precision machine tool for micro manufacturing applications. The measurement system can be effectively integrated into the working volume of different types of machines allowing both tool and workpiece measurements and avoiding its disassembly from the machine stage for off-line measurements and, consequently, reference losses. The fast measurements of tool and workpiece during the machining contribute to increase the accuracy and reduce the overall machining-measurement iterations. The assessment is achieved by a test case where a low cost USB microscope is applied to a micro-EDM machine. The low cost device has been applied for tool electrode measurements and tool wear evaluation after an accuracy enhanced calibration procedure and high performance image processing algorithms, which effectively reduce the lack of the hardware performance. The measurement performance gives a feedback on the deviations of the machined features from nominal geometry and allows their compensations by an adequate machining strategy.

Due to its ability to produce low-cost and high repeatable micro-polymeric parts, micro-injection molding is emerging as one of the most promising enabling technologies in many different fields. When approaching the micro-scale, different issues related to the process should be addressed, especially as the thickness of the cavities becomes very thin. In particular, the mold roughness affects the surface quality of the micro-components produced, like in macro-molding, but this could also encompass the complete filling of the parts. The main objective of the present paper is to evaluate the roughness influence of the mold on the non-Newtonian fluid flow during the micro-injection process in thin micro-cavities where the mold surface condition could affect the process due to the phenomena neglected in macro- or mesoscale as less important boundary conditions. The part design was properly conceived in order to neglect the effect of dimensions and geometry and to highlight the roughness contribution during the filling phase. The experimentation was performed using cavities with different roughness values and decreasing depths from 200 to 50 μm, considerably lower than 250 μm found in literature and manufactured by the micro-electrical discharge machining (μ-EDM). The results of the experiments are discussed and show that cavity-surface roughness affects the process as the molding scale is decreased. In particular, in thin cavities, higher surface roughness promotes the filling of component.

Electro discharge machining (EDM) is one of the most widely used non-conventional and contactless technologies for the manufacturing of materials featuring electro-conductivity, high hardness and strength. The functioning principle is based on a series of discrete electrical discharges occurring in between two electrodes, the tool and the workpiece. EDM includes different technological approaches: wire, drilling, sinking and milling. Micro-EDM allows to machine micro-features and devices for many applications in industry, aeronautics and recently in the medical field. In this chapter, fundamental issues related to micro-EDM are addressed and some common strategies for the evaluation of machining performance are presented. Moreover, representative examples on the efficient use of such technology and related approaches are reported.

In spite of significant improvements in micro-replication techniques, methods to fabricate well-defined net shape microstructures are still in a developing stage. Soft lithography has the capability to manufacture complex micro- and nanostructures. Although it is considered a robust technique, a major limitation is related to the distortion encountered in the fabricated structures during the drying process. In the present work, a manufacturing technology has been developed that emerges the benefits of soft lithography and micro-electrical discharge machining (μ-EDM) to produce stainless steel precise micro-components for micro-implantable devices. The micro-parts produced by soft lithography were subsequently surface processed via μ-EDM in order to improve the surface quality. In addition to this, it was found that μ-EDM drastically improved the surface roughness of stainless steel micro-components from Ra = 3.4 μm to Ra = 0.43 μm.

Unlike materials subtractive technologies, additive manufacturing (AM) works on producing near-net-shape components according to a specific design at which the synthesis is achieved layer by layer. Additive manufacturing allows design freedom, making design-driven manufacturing a reality. However, its poor surface quality is considered as one of the key challenges that are worth to overcome. The main objective of this chapter is to report a comprehensive overview of the techniques used to improve the surface finish and their advancements of products made by metal additive manufacturing (AM) technologies and to highlight experimental processes and data. Powder bed fusion (PBF) and direct laser deposition (DLD) are the main processes covered in this review. The chapter starts with the literature review and introduction to the main metal AM processes and their surface roughness limitations, the effect of their parameters and the effect of the laser re-melting on the surface quality. Next, it is followed by a number of surface finishing techniques such as laser polishing, chemical and electropolishing. Experimental results of post-surface finishing of AM parts by microelectrical discharge machining are also presented.

In this work, the implementation of an energetic model capable of predicting the energy consumption of a micro-electro discharge (micro-EDM) machine is presented. The developed model requires two main inputs: the estimate of the power absorbed by each subsystem composing the machine tool and the operation times, which includes the machining times. The power contributions can be determined via machine data sheets and via measurements. The energy consumption of a machine tool is due to two main contributions, ascribed to auxiliary units and to the manufacturing process itself. The developed model has been validated considering the micro-EDM milling of a circular pocket. The comparison between the estimated and measured energy consumption shows that the model is not only very accurate, but also very sensitive to the correct estimate of the machining times. Indeed, when the correction of the erosion time is operated by considering the actual value obtained by experiments instead of the one estimated by the CAD/CAM, the error referring to each energy contribution estimated by the model is greatly reduced. Furthermore, it can be noticed that most of the energy consumed by the micro-EDM manufacturing is actually inferable to the chiller unit.

L'obiettivo di ibridizzare le tecnologie di elettroerosione e getto d'acqua abrasivo nasce dall'esigenza di sfruttarne al meglio le potenzialità e rimediare, al tempo stesso, alle criticità di entrambi. Questo può essere considerato il motivo principale che spinge la ricerca verso uno studio di fattibilità di un'ibridizzazione così innovativa. Un piano sperimentale è stato messo a punto nel tentativo di valutare la possibilità di lavorare con i due processi su di uno stesso centro di lavoro, operando con lo stesso fluido. A tal proposito è stata analizzata l'influenza della conducibilità del fluido sul processo di asportazione del materiale per elettroerosione, messe in evidenza delle limitazioni sul processo in regimi a bassa energia di scarica tipici della micro-EDM, ed infine ricercata una condizione di lavoro che massimizzasse il tasso di volume di materiale asportato.

The mechanical behaviour of specimens fabricated using FDM machine has been thoroughly studied and several works have been presented. However, they are focused on few materials, in particular ABS, while very few papers analysed the mechanical properties of FDM samples made by PLA filament. Even though ABS is well known for its superior mechanical properties, some applications might require materials with other properties, such as PLA. Therefore, a deeper investigation of the effect of the process on its properties is needed. In this study, at first, the influence of the main FDM process parameters, such as raster angle, extrusion width, air gap and extrusion temperature, on mechanical performance of PLA samples has been evaluated. The mechanical tests have been carried out on miniaturized tensile specimens focusing on the tensile test main properties: ultimate tensile stress, Young modulus and elongation at break. Moreover, an experimental campaign has been carried out on the effect of a thermal post-processing, in order to evaluate the effects of the treatment and its relation with the process parameters on the mechanical properties of the specimens.

In the present paper, a numerical approach to model the layer-by-layer construction of cured material during the Additive Manufacturing (AM) process is proposed. The method is developed by a recursive mechanical finite element (FE) analysis and takes into account forces and pressures acting on the cured material during the process, in order to simulate the behavior and investigate the failure condition sources, which lead to defects in the final part geometry. The study is focused on the evaluation of the process capability Stereolithography (SLA), to build parts with challenging features in meso-micro scale without supports. Two test cases, a cantilever part and a bridge shape component, have been considered in order to evaluate the potentiality of the approach. Numerical models have been tuned by experimental test. The simulations are validated considering two test cases and briefly compared to the printed samples. Results show the potential of the approach adopted but also the difficulties on simulation settings.

Due to its ability to produce low-cost and high repeatable micro polymeric parts, injection moulding of micro components is emerging as one of the most promising enabling technologies for the manufacturing of polymeric micro-parts in in many different fields, from IT to Healthcare, to Medicine. However, when approaching the micro-scale, different issues related to the process should be addressed, especially as the depth of the mould cavity becomes very thin. In particular, the mould roughness could affect the surface quality of the produced micro components, like in macro moulding, as well as the complete filling of the parts. Although micro-injection moulding process has been extensively studied, further research on the effect of mould roughness conditions and on non-Newtonian fluid flow in micro-cavities are required. This will shed a light and open up new paths for a deeper understanding of the moulding scenario. The main objective of the present paper is the evaluation of the influence of the mould roughness on the polymer flow during micro injection moulding process. The test parts have been realized in POM material and have thickness lower than 250 μm. The test part design has been properly conceived in order to neglect the effect of dimensions and geometry and to highlight the roughness contribution during the filling phase of micro injection moulding process. The experimentation has been performed considering cavities with different roughness values (3 levels) and decreasing depths (3 levels), for a total of nine test parts manufactured by micro-electrical discharge machining process (μ-EDM). The results of the experiments are discussed in the paper and show that cavity surface roughness affects the injection process as the moulding scale level is decreased. In particular, when the cavity depths are reduced, higher surface roughness promotes the filling of components and this finding could be ascribed to the increase of wall slip effect.

A comparison of the machining performance of micro-electro-discharge machining (EDM) milling and sinking is proposed considering the fabrication of microchannels with controlled sloped walls realized in a hardened steel workpiece. Adopting the fine-finishing machining regime for both micro-EDM techniques, the experimental results show that micro-EDM sinking is about ten times faster than milling in the worst case, though a lack of accuracy in the final microfeatures in the former case is detected due to not compensated tool wear. On the contrary, micro-EDM milling provides a better control of the microchannel dimensions. Finally, a microfilter mold for medical applications is machined in order to show the potential of the combination of both technologies.

Le industrie manifatturiere avanzate, utilizzando tecniche di lavorazione di precisione, come il diamond turning (tornitura con utensili in diamante), lo stampaggio a iniezione, la micro-fresatura e la micro-lavorazione per elettroerosione, sono in grado di produrre componenti in miniatura complessi, ad alta precisione. Accanto alle tecnologie di micro-lavorazione è necessario, però, possedere una serie di competenze per la misura di strutture di piccole dimensioni con tolleranze in scala micro [1]. La metrologia è essenziale per la riduzione delle tolleranze dimensionali, che permette la produzione di macchine più efficienti e il miglioramento della loro longevità, riducendo i giochi o l'usura. Un esempio sono gli ugelli di iniezione più piccoli e più efficienti nelle macchine a combustione, la cui produzione è strettamente legata al miglioramento delle capacità di misura dimensionale. Altri esempi sono la radiofrequenza o i componenti dei connettori di fibre ottiche, in cui le dimensioni caratteristiche e le tolleranze richiedono un'incertezza di misura a livello di 0,1 ?m, oppure le piccole lenti asferiche/freeform delle fotocamere digitali o dei telefoni cellulari [2]. Un settore emergente è quello dei prodotti medicali ad alta tecnologia, che molto spesso dipendono notevolmente da piccoli componenti; tra questi vi sono, ad esempio, le pompe per insulina, gli stimolatori cardiaci, i sensori per la diagnostica in vivo o i sistemi di visione endoscopici. In questo capitolo vengono descritte le tecniche a contatto e non a contatto che possono essere utilizzate per misurare feature 3D in scala micrometrica.

This paper reports on design, fabrication, and characterization of a microfilter to be used in biomedical applications. The microfilter, with mesh of 80 μm, is fabricated by micro-injection molding process in polymeric material (polyoxymethylene (POM)) using a steel mold manufactured by micro-electrical discharge machining process. The characteristics of the filter are investigated by numerical simulation in order to define a suitable geometry for micro-injection molding. Then, different process configurations of parameters (melt temperature, injection velocity, mold temperature, holding pressure and time, cooling time, pressure limit) are tested in order to obtain the complete part filling via micro-injection molding process preventing any defects. Finally, the component is dimensionally characterized and the process parameters optimized to obtain the maximum filtration capacity.

l'obiettivo è quello di caratterizzare, quindi valutare e quantificare in maniera oggettiva, le prestazioni della tecnica fotogrammetrica "close range" applicata a metrologia micrometrica o "micro-features" utilizzata presso il Politecnico di Bari. Inizialmente sono fornite la classificazione delle diverse tecniche di acquisizione dati 3D con focus sulle tecniche senza contatto, le definizioni dei parametri metrologici secondo le norme vigenti e la descrizione della linea guida VDI/VDE 2634 e delle diverse ipotesi di sviluppo di uno standard condiviso che permetti di caratterizzare metrologicamente gli strumenti di misurazione ottica 3D. Successivamente, invece, sono presentati i due strumenti ottici passivi utilizzati, in particolare i principi geometrici-analitici alla base della fotogrammetria e i principi di funzionamento della microscopia confocale. Infine sono descritti gli strumenti e le fasi che caratterizzano il sistema fotogrammetrico applicato al Politecnico di Bari e la metodologia e le analisi sperimentali effettuate per l'applicazione della linea guida VDI/VDE 2634, utile alla validazione e caratterizzazione del sistema in questione. In particolare, per poter portare a termine tale fase è stato necessario svolgere un tirocinio della durata di tre mesi presso l'Istituto di Tecnologie Industriali ed Automazione (ITIA) sezione di Bari del Consiglio Nazionale delle Ricerche (CNR) sotto la supervisione del tutor aziendale, nonché correlatore, ingegner Modica Francesco. La "Wire EDM" ha permesso, attraverso il processo di elettroerosione, la realizzazione dei micro manufatti utili alla caratterizzazione e validazione metrologica della tecnica fotogrammetrica applicata al Politecnico di Bari. Mentre, il microscopio confocale CSM 700 ha permesso l'acquisizione, la digitalizzazione e la misurazione degli stessi manufatti realizzati con la "Wire EDM", che saranno il riferimento del confronto dei dati misurati con la tecnica fotogrammetrica che si vuole caratterizzare.

The fabrication of personalized implants, tailored on patient needs, is a key issue for the future of several surgical fields. The presence of a prototyping service inside the hospital would be an added value for improving clinical activity. In this context, micro-Electro Discharge Machining is exploited to customize fixation devices in orthopedic surgery. An overview of the main devices is carried out in order to identify the main characteristics and to define the common fixation system specifications. The experimentation includes a technological evaluation of the proper micro-EDM technology, chosen according to the final design of the components. Two materials are investigated for the device fabrication: titanium and Si3N4-TiN ceramic composite. An optimization of the main technological parameters is performed in order to maximize the material removal rate ensuring the accuracy of the micro-features required. Finally, a test case is selected in order to evaluate the entire fabrication process chain.Copyright © 2015 by ASME

This paper reports the comparison of the machining performance of micro-EDM milling and sinking for the fabrication of micro-channels with controlled sloped walls realized in a hardened steel workpiece. The machining regime used for both micro-EDM sinking and milling is the fine-finishing. The results show that micro-EDM sinking is about 9 times faster than milling, though the effects of tool wear become relevant inducing a lack of accuracy in the final micro-features. Despite the slower machining time, micro-EDM milling provides a better control of the micro-channel dimensions and draft angles of the walls. No difference related to surface roughness is detected, since the energy level used in both approaches is the same. A micro-filter for hearing aid, dialysis media and inhaler, having a diameter of 2.3 mm characterized by a grid of 76 micro-pins, is machined in order to show the potential of the combination of both technologies.

In this paper, the pulse discrimination of gap voltage and discharge current waveforms occurring during micro-EDM milling of micro-channels is analyzed in relation to process parameters variation and machining performance. The pulse classification algorithm discriminates voltage and current waveforms into four defined pulse types: short, arc, delayed and normal. The micro-channels are manufactured in hardened steel using an energy level corresponding to the finishing regime and varying pulse width, frequency, gain and gap. The analysis shows that when the erosion process is stable, normal discharges are predominant. Delayed and short pulses are very sporadic. A major number of arcs can be detected when the gap is decreased and gain increased, i.e. erosion speed and feed rate are increased and affect in particular tool wear. Also the increase of the pulse width has an effect on tool wear, though the percentage of the arcs remains small. On the contrary, material removal rate does not seem to be apparently related to the percentage of arcs as the process parameters are varied, since these values are spread in a constant range for all parameter combinations. The evaluation of the depth errors does not provide any significant insights about the erosion process in relation to the considered process parameters.

This paper discusses the applications and development of magnetic actuators for meso-scale mechanisms. Due to their small sizes, meso-scale parts cannot be actuated using techniques typical of macro-scale mechanisms, such as servos or ball screws. Similarly, the techniques used in micro-actuation, such as the use of electrostatic force in MEMS devices, cannot be easily scaled up to the meso-scale. As a result, the use of magnetic forces for actuating meso-scale mechanisms may be capable of filling this void of actuation methods. A case study of a fixturing mechanism meant for meso-scale end-milling was analyzed. This mechanism uses two fixed-fixed beams in order to actively tune the harmonic modes of the machining operation in order to improve the stability of the cutting. It also uses magnetic forces to actuate the fixturing platform in order to provide close-loop feedback of cutting force. This mechanism was then scaled down to create a meso-scale mechanism that can be used for a variety of purposes. It is possible that this research could have applications in biomedicine, where magnets can be used to remotely actuate clamping devices; consumer electronics, where it can provide added stability for devices such as digital video cameras; and small satellites, where it can be used to help prevent damage to fragile parts

Si riportano in questo documento alcune misure dello stampo, usato per il micro stampaggio ad iniezione, prese attraverso il microscopio confocale CSM700 della ZEISS. Le immagini utilizzate per le misure sono state acquisite attraverso la ricomposizione panoramica (pacthwork), via software proprietario, di frame successivi lungo gli assi x ed y ed in scansione lunga l'asse z.

Aluminum alloys offer many machining advantages, such as excellent machinability and finish degree, outstanding tool life, and good corrosion resistance. They also display an elevated thermal exchange and weight reduction, which lead to easier handling compared to steels and make them good candidates for applications in the automotive and aerospace industry and in the field of mould production. Despite these recognized features, the machining accuracy, in particular in the micro-electro discharge machining (micro-EDM) process, needs further improvement. Revealing the nature of the Al alloys in EDM machining, some papers report of resolidifying layers in Al alloys appearing after the EDM process and grain compositions hugely affecting surface roughness. In particular, it has been observed that a thin and strong insulating layer due to the oxidation of the aluminum workpiece after machining leads to frequent tool breakage. In practice, this makes the micro-EDM process harder when micro-tools are meant to be used. However, to the best of our knowledge, the investigation of micro-EDM process performances of Al-Mg has not yet been fully explored. In this work, micro-EDM Al-Mg machining is presented: different energy levels were tested to find the proper parameter combination feasible to process micro-features. The machining geometrical limits are also investigated, putting in relation the energy levels to different electrode tool diameters. The experimental results are discussed on the basis of the evaluation of material removal rate (MRR), tool wear ratio (TWR), surface roughness and sparking gap. The machining of a micro-shaft housing component featuring high aspect ratio (HAR) is also shown as demonstrator to prove the effectiveness of the micro-EDM parameters selected from the previous trials.Copyright © 2012 by ASME